Using a flying observatory called Stratospheric Observatory for Infrared Astronomy (SOFIA), NASA has confirmed that there is water on the sunlit surface of the Moon in one of the largest craters visible from Earth named Clavius Crater. The water at this location is in concentrations of 100 to 412 parts per million or the same amount you’d find in a 12-ounce bottle of water.
If you were to ask most people, they’d tell you that there’s no water in the desert but apparently there is. According to NASA, the Sahara desert has 100 times the amount of water than what SOFIA was able to find in the lunar soil. The agency said despite the amount being small, it now raises questions about how water can persist “on the harsh, airless lunar surface.”
Discussing the findings, Casey Honniball, the lead author on the paper detailing the findings, said:
“Without a thick atmosphere, water on the sunlit lunar surface should just be lost to space. Yet somehow we’re seeing it. Something is generating the water, and something must be trapping it there.”
Now that we know that there’s water on the sunlit portion of the Moon, scientists want to answer two more questions: how is it getting there? And how is it stored?
In terms of how the water gets there, NASA has a few theories. One suggests that micrometeorites are raining down on the lunar surface carrying small amounts of water that could be deposited on impact. Another suggestion is that the Sun’s solar wind delivers hydrogen to the lunar surface and then undergoes a chemical reaction with oxygen-bearing minerals in the soil to create hydroxyl. Radiation from the barrage of micrometeorites could then be transforming the hydroxyl into water.
Regarding the storage of the water, NASA suggests that it could be trapped in tiny beadlike structures in the soil that are formed out of high heat created by micrometeorite impacts. Another possibility is that the water is hidden between grains of lunar soil and sheltered from the sunlight.
SOFIA will continue its observation of the Moon in additional sunlight locations and during different lunar phases to learn more about the production, storage, and movement across the Moon. Understanding the nature of water on the Moon will be essential to future lunar missions including Artemis that will see the first woman and the next man land on the Moon in this decade.